Existence: Is there more than one me?

FAR, far away, in a galaxy with a remarkable resemblance to the Milky Way, is a star that looks remarkably like the sun. And on the star’s third planet, which looks like a twin of the Earth, lives someone who, for all the world, is you. Not only do they look the same as you and lead an identical life, they are reading this exact same article – in fact, they are focused on this very line.

Weird? I’ve hardly started. In fact, there are an infinite number of galaxies that look just like our own, containing infinite copies of you and your loved ones leading lives, up until this moment, that are absolutely identical to yours.

The existence of these parallel worlds is not just idle speculation. It does not depend on exotic theories such as the multiverse or the “many worlds” interpretation of quantum mechanics, in which the universe constantly bifurcates. It is an unavoidable consequence of the standard theory of our universe.

Parallel worlds are an unavoidable consequence of our standard theory

All this needs some explanation. The furthest we can see is the distance light has been able to travel since the universe was born 13.7 billion years ago. Light from objects further away has not arrived yet. They are beyond our cosmic horizon.

Yet we know there is more to the universe. Radiation left over from the big bang appears to confirm that the cosmos went through a fleeting phase of superfast expansion known as inflation. And, according to inflation, there is effectively an infinite …